Raw materials to be treated in accordance with the invention consist primarily of packaging waste containing metallic aluminium, which in addition to aluminium foil comprise polymer material and possibly also fibre residues. The treatment aims to utilise the calorific power of the organic matter and/or to recover the valuable aluminium or other similar metal.
The utilisation of such waste material containing aluminium for energy production has been very difficult or even impossible to control by means of combustion or gasification techniques known so far. The problems have been due to the ash component, which melts at a low temperature considering the conversion techniques applied, and thus tends to form detrimental deposits on the walls of the reaction space, and also to cause sintering of the fluidised bed and other process failures. At the same time, in the cases where aluminium recovery has been the aim, the recovery has been deficient.